predicates/str/
difference.rs

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1// Copyright (c) 2018 The predicates-rs Project Developers.
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9use std::borrow;
10use std::fmt;
11
12use crate::reflection;
13use crate::Predicate;
14
15/// Predicate that diffs two strings.
16///
17/// This is created by the `predicate::str::diff`.
18#[derive(Debug, Clone, PartialEq, Eq)]
19pub struct DifferencePredicate {
20    orig: borrow::Cow<'static, str>,
21}
22
23impl Predicate<str> for DifferencePredicate {
24    fn eval(&self, edit: &str) -> bool {
25        edit == self.orig
26    }
27
28    fn find_case<'a>(&'a self, expected: bool, variable: &str) -> Option<reflection::Case<'a>> {
29        let result = variable != self.orig;
30        if result == expected {
31            None
32        } else {
33            let palette = crate::Palette::new(true);
34            let orig: Vec<_> = self.orig.lines().map(|l| format!("{l}\n")).collect();
35            let variable: Vec<_> = variable.lines().map(|l| format!("{l}\n")).collect();
36            let diff = difflib::unified_diff(
37                &orig,
38                &variable,
39                "",
40                "",
41                &palette.expected("orig").to_string(),
42                &palette.var("var").to_string(),
43                0,
44            );
45            let mut diff = colorize_diff(diff, palette);
46            diff.insert(0, "\n".to_owned());
47
48            Some(
49                reflection::Case::new(Some(self), result)
50                    .add_product(reflection::Product::new("diff", diff.join(""))),
51            )
52        }
53    }
54}
55
56impl reflection::PredicateReflection for DifferencePredicate {
57    fn parameters<'a>(&'a self) -> Box<dyn Iterator<Item = reflection::Parameter<'a>> + 'a> {
58        let params = vec![reflection::Parameter::new("original", &self.orig)];
59        Box::new(params.into_iter())
60    }
61}
62
63impl fmt::Display for DifferencePredicate {
64    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
65        let palette = crate::Palette::new(f.alternate());
66        write!(
67            f,
68            "{:#} {:#} {:#}",
69            palette.description("diff"),
70            palette.expected("original"),
71            palette.var("var"),
72        )
73    }
74}
75
76/// Creates a new `Predicate` that diffs two strings.
77///
78/// # Examples
79///
80/// ```
81/// use predicates::prelude::*;
82///
83/// let predicate_fn = predicate::str::diff("Hello World");
84/// assert_eq!(true, predicate_fn.eval("Hello World"));
85/// assert!(predicate_fn.find_case(false, "Hello World").is_none());
86/// assert_eq!(false, predicate_fn.eval("Goodbye World"));
87/// assert!(predicate_fn.find_case(false, "Goodbye World").is_some());
88/// ```
89pub fn diff<S>(orig: S) -> DifferencePredicate
90where
91    S: Into<borrow::Cow<'static, str>>,
92{
93    DifferencePredicate { orig: orig.into() }
94}
95
96#[cfg(feature = "color")]
97fn colorize_diff(mut lines: Vec<String>, palette: crate::Palette) -> Vec<String> {
98    for (i, line) in lines.iter_mut().enumerate() {
99        match (i, line.as_bytes().first()) {
100            (0, _) => {
101                if let Some((prefix, body)) = line.split_once(' ') {
102                    *line = format!("{:#} {}", palette.expected(prefix), body);
103                }
104            }
105            (1, _) => {
106                if let Some((prefix, body)) = line.split_once(' ') {
107                    *line = format!("{:#} {}", palette.var(prefix), body);
108                }
109            }
110            (_, Some(b'-')) => {
111                let (prefix, body) = line.split_at(1);
112                *line = format!("{:#}{}", palette.expected(prefix), body);
113            }
114            (_, Some(b'+')) => {
115                let (prefix, body) = line.split_at(1);
116                *line = format!("{:#}{}", palette.var(prefix), body);
117            }
118            (_, Some(b'@')) => {
119                *line = format!("{:#}", palette.description(&line));
120            }
121            _ => (),
122        }
123    }
124    lines
125}
126
127#[cfg(not(feature = "color"))]
128fn colorize_diff(lines: Vec<String>, _palette: crate::Palette) -> Vec<String> {
129    lines
130}
predicates/str/difference.rs

predicates/str/
difference.rs
